A typical use for a swivel of the above type is in an industrial robot, and the invention will be exemplified by reference to this use. However, the invention is not so limited; it may be utilized in many applications within the scope of the appended claims.
In a swivel media like compressed air, cooling liquid, lubricant, electric power, and/or control signals, i e generally fluids and or electricity, are to be transferred between the two coaxial, mutually rotatable members.
With regard to fluid transfer the two members are rotating against each other, and the cooperating surfaces of the members are provided with mutually corresponding circular grooves, so that fluid may be transferred from one member to the other irrespective of their mutual angular position. A known problem with this type is the sealing between the members and around the grooves.
Electric transfer may be provided by slip ring devices in or at the swivel. These devices, which are separate from the fluid transfer, are susceptible of wear and negative influences of dirt, dust and the like.
A swivel of this type is relatively complicated and therefore time-consuming and expensive to manufacture. In spite of this the number of different fluids that can be transferred is limited.
Due to the complicated construction it is difficult to service the device, and the life-span is relatively short.